Currently, in our country, as alcoholic beverages produced with malt, beers and sparkling liquors are consumed much. Sparkling liquors are produced with a smaller amount of malt as compared with beers and, in accordance with the Liquor Tax Act, beverages produced with malt in an amount of 66.7% by weight or more of total raw materials except for water are classified into beers, and beverages produced with malt in the amount of less than 66.7% by weight are classified into sparkling liquors. Further, recently, subsequent to “beers” or “sparkling liquors”, beverages so-called “third beers” are sold on the market. As the “third beers”, there are beers produced without any malt as raw materials and beers in which other alcoholic beverages are mixed in beers or sparkling liquors, and they are produced with a smaller amount of malt as compared with beers, similarly. In accordance with the Liquor Tax Act, the former is classified into “other brewed liquors (sparkling) (1)” or “other miscellaneous liquors (2)”, and the latter is classified into “liqueurs (sparkling) (1)”.
Meanwhile, bubbles of beers have important functions such that beers taste as good as their looks, a carbonic acid gas is suppressed from escaping to the outside, degradation of beers due to contact with the air is prevented to retain a taste, a flavor is generated by foaming, and the like. For these reasons, improvement in bubble retention is an important factor for making beers having better quality. This is not limited to beers, but is also similar to sparkling liquors which are substitute beverages for beers, and the third beers. However, in beer-like beverages in which an amount of malt to be used is suppressed as described above, there is a problem that bubble retention is inferior as compared with beers. This is because a protein and a carbohydrate derived from malt contribute to bubble retention of beers.
In order to solve such a problem, for example, Patent Document 1 discloses a technique of using saponin, a thickener or the like as a bubble retention improving agent in a sparkling liquor, Patent Document 2 discloses a technique of using a pea protein extracted from peas as a bubble retention improving substance in a sparkling alcoholic beverage, and Patent Document 3 discloses the use of a sorghum degradation product in a sparkling liquor. However, all of them have a rough feeling, and have insufficient bubble retention effects.
On the other hand, in carbonated refreshing beverages in which carbonic acid is contained in the beverages such as a soda pop, a cola, and a juice, there is no bubble retention due to a protein. A refreshing feeling due to bubbles is felt, but produced bubbles are rough, the bubble retention is also worse, and stimulation with carbonic acid is too strong and, thus, the beverages are not necessary preferable from the viewpoint of a palate. For this reason, in the carbonated refreshing beverages, a technique of producing fine bubbles, and capable of improving the bubble retention is also demanded.
In order to solve such problem of the carbonated refreshing beverages, Patent Document 4 discloses a process for producing a high sparkling refreshing beverage having such a composition that a raw material solution contains a saponin ingredient and a carbonic acid gas, and Patent Document 5 discloses a process for producing a sparkling luxury beverage having improved foaming and bubble retention, which comprises preparing a luxury beverage by incorporating saponin or a saponin containing preparation, and an oligosaccharide, or an oligosaccharide and a polysaccharide together therein, and carbonating the beverage. However, in these techniques, bitterness due to the saponin ingredient is problematic. The present applicants have previously filed an application directed to a food foaming agent and a foaming stabilizer containing, as an active ingredient, a water-soluble hemicellulose extracted from an oil stuff seed including a soybean (Patent Document 6). However, the agent is aimed at shake beverages such as a milkshake or similar products, and its effect on sparkling beverages in the present invention has still a room for improvement.    Patent Document 1: WO 04/000990    Patent Document 2: WP 05/005593    Patent Document 3: JP 2006-204172 A    Patent Document 4: JP 61-92554 A    Patent Document 5: JP 5-38275 A    Patent Document 6: JP 5-244880 A